This invention generally relates to catalysts. More particularly, the invention relates to polymer-containing organo-metal catalysts useful in the polymerization of macrocyclic oligoesters.
Linear polyesters such as poly(alkylene terephthalate) are generally known and commercially available where the alkylene typically has 2 to 8 carbon atoms. Linear polyesters have many valuable characteristics including strength, toughness, high gloss, and solvent resistance. Furthermore, polyesters may be fabricated into articles of manufacture by a number of well-known techniques including injection molding, roto-molding, and extrusion.
Recently, macrocyclic oligoesters were developed as precursors to polyesters. Macrocyclic oligoesters exhibit low melt viscosity, which can be advantageous in certain applications. Furthermore, certain macrocyclic oligoesters melt and polymerize at temperatures well below the melting point of the resulting polymer. Upon melting and in the presence of an appropriate catalyst, polymerization and crystallization can occur virtually isothermally.
Catalysts that may be used in the polymerization of macrocyclic oligoesters include various organo-metal compounds, including conventional, non-polymer-containing organotin compounds and titanate esters. It is desirable to have organotin compounds and titanate esters that are less moisture sensitive so that they may be stored and handled with ease in ambient air. Such catalysts are more suitable for preparing a stable and easy-to-handle blend material of a macrocyclic oligoester and a polymerization catalyst (i.e., a one-component ready-to-use mixture).
Furthermore, the required volume ratio of a macrocyclic oligoester to a conventional catalyst (e.g., organotin compounds or titanate esters) is very high, typically greater than 100:1. See, e.g., U.S. Pat. No. 5,466,744 to Evans et al. The high volume ratio requires sophisticated and costly metering and mixing equipment to properly introduce and disperse the relatively small amount of catalyst. This is of particular concern in liquid molding applications.
Novel polymer-containing organo-metal catalysts have been prepared that are much less sensitive to moisture and that have much larger molar volume and much greater molecular weight. Such polymer-containing organo-metal catalysts are particularly useful for the polymerization of macrocyclic oligoesters in liquid molding applications. In addition, these catalysts are well-suited for preparing a blend material of a macrocyclic oligoester and a catalyst where the blend is stable at ambient storage conditions.
In one aspect, the invention is directed to a polymer-containing catalyst that includes a compound of the formula
(R1xe2x80x94Y1xe2x80x94)i-M"Parenopenst"Y2xe2x80x94R2)j.
Each R1 may be an alkyl group or an alkyl ether group, each having between 1 and 20 carbon atoms. Additionally, two or more R1 groups may be attached, thereby forming either an alkyl group or an alkyl ether group having between 1 and 20 carbon atoms. Each R2 independently is a polymeric group containing 25 or more carbon atoms, and at least one R2 includes a polyalkylene group of 25 or more carbon atoms, a polyether group, or both. In addition, i is an integer equal to or greater than zero, while j is an integer equal to or greater than one. Each Y1 and Y2 is either a single bond or a heteroatom selected from the group consisting of O, S, and N. M is a metal-containing group, and may be Ti, Sn, or -Z1-(X)k-Z2-, where each of Z1 and Z2 independently is Ti or Sn, and each X independently is O or Oxe2x80x94R3xe2x80x94O, where R3 is an alkylene group, and k is 1, 2, or 3.
In another aspect, the invention is directed to a polymer-containing catalyst that is prepared by chemically bonding a titanium-based catalyst or a tin-based catalyst with one or more polymeric groups. Each of the one or more polymeric groups contains 25 or more carbon atoms. One or more of the polymeric groups includes a polyalkylene group that has 25 or more carbon atoms, a polyether group, or both.
In yet another aspect, the invention is directed to a polymer-containing catalyst having the molecular formula
Ti"Parenopenst"OR)4,
where each R independently is a polymeric group having 25 or more carbon atoms.
In yet another aspect, the invention is directed to a polymer-containing catalyst having the molecular formula
(R1xe2x80x94)2xe2x80x94Sn"Parenopenst"OR2)2.
Each R1 independently is, or two R1 groups taken together are, an alkyl group or an alkyl ether group each having between 1 and 20 carbon atoms. Each R2 independently is a polymeric group having 25 or more carbon atoms.
In yet another aspect, the invention is directed to a method of preparing a polymer-containing organo-metal catalyst. The method generally includes the steps of providing an organo-metal compound that contains an alkoxy metal moiety; providing a polymer containing 25 or more carbon atoms, a hydroxyl group, and a polyalkylene group and/or a polyether group; and contacting the organo-metal compound and the polymer at an elevated temperature. The chemical reaction between the alkoxy metal moiety of the organo-metal compound and the hydroxyl group of the polymer produces the polymer-containing catalyst.
In yet another aspect, the invention is directed to a blend material that contains a macrocyclic oligoester and a polymerization catalyst. The macrocyclic oligoester includes a structural repeat unit of the formula 
where A is an alkylene, a cycloalkylene, or a mono- or polyoxyalkylene group; and B is a divalent aromatic or alicyclic group. The polymerization catalyst contains a polymeric group that has 25 or more carbon atoms.
In yet another aspect, the invention is directed to a method for polymerizing a macrocyclic oligoester. The method includes the step of contacting a macrocyclic oligoester and a polymerization catayst at an elevated temperature. The polymerization catalyst has a polymeric group with at least 25 carbon atoms.
In yet another aspect, the invention is directed to a method for polymerizing a macrocyclic oligoester. The method includes the steps of providing a molten macrocyclic oligoester in a mold; providing a molten polymerization catalyst in the mold; and contacting the molten macrocyclic oligoester and the molten polymerization catalyst inside the mold, thereby causing polymerization of the macrocyclic oligoester. The polymerization catalyst contains a polymeric group having 25 or more carbon atoms.
In yet another aspect, the invention is directed to a polymer-containing catalyst that is prepared by bonding a catalyst with one or more polymeric groups. Each of the one or more polymeric groups contains 25 or more carbon atoms. One or more of the polymeric groups includes a polyalkylene group that has 25 or more carbon atoms, a polyether group, or both.